/**
 *	用迭代方法计算第 n 个斐波那契数的值
**/

long fibomacci(int n)
{
	long result;
	long previous_result;
	long next_older_result;

	result = previous_result = 1;

	while(n > 2)
	{
		n -= 1;
		next_older_result = result;
		previous_result = result;
		result = previous_result + next_older_result;
	}
	return result;
}
